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The electric aircraft propellers you see now are all open structures, which are currently sufficient for UAV applications. However, as electric aircraft become larger and larger, they require greater load requirements for people and cargo. , as well as improving endurance capability, put forward higher design requirements for aircraft propeller systems.

So let’s compare the impact of propeller designs with different structures on electric aircraft from the following displays of several propeller structures.

The picture above is a popular open propeller system with a simple and practical structure. If you want the propeller to exert greater thrust, increasing the motor power and speed is one solution, but this will put greater pressure on the battery power supply system. , directly affecting the endurance of electric aircraft.

Then by placing the propeller in the duct, the air intake volume can be effectively increased, and the thrust of the propeller can be increased. Let's take a look at the comparison of open and ducted propeller structures.

The efficiency of the open propeller system is only 85%-90% of that of the ducted propeller. At the same time, it has greater noise and safety issues. When rotating, it poses certain safety risks to personal safety and the propeller.

So are there any disadvantages to ducted propeller fans? Why are they rarely used in drones and electric aircraft?

Duct propeller fans have higher power requirements for the overall system, and also have a certain structure, which increases air resistance and the weight of the system. So is there a better design to solve this problem?

The bell-mouth propeller duct fan design can effectively increase the air intake volume and reduce losses. Then the channel propeller system designed as an adaptive retractable will have higher efficiency, thrust and adaptability.

When the adaptive retractable duct propeller fan is in the open state, it can generate a larger amount of air in the duct, increase thrust during vertical takeoff and landing, and increase takeoff weight. In the retracted state, it has better aerodynamic effects, reduces wind resistance, and is suitable for cruising and straight flight of electric aircraft.

When the pipe is open, the efficiency can be increased by 40%. For electric aircraft with multiple propeller systems, it will have greater thrust and effectively reduce the weight of the overall motor aircraft. Then let’s take a look at the principle prototype test comparison between the open state and the retracted state to see if the effect can be improved so much.

As can be seen in the picture, when the open state is opened, a larger area is added to increase the air intake volume, while when the retracted state is reached, the duct has a smaller cross-section, reducing wind resistance, which is conducive to cruising flight.

In the proof-of-concept prototype test, the maximum air volume in the contracted state was 18m3/h. When in the open state, it can reach 33m3/h, which increases the thrust by 20%.

On the premise of a propeller structure with greater thrust, higher efficiency and better adaptability, the performance of the entire electric aircraft is improved, and it also has greater advantages in the size and weight of the entire aircraft. So what is the difference in dimensions between variable ducted propellers, ducted propellers and open propellers?

As can be seen in the figure, the outer diameter and axial dimensions of different propulsion systems are quite different. The adaptive retractable duct propeller will also have greater advantages in size and weight.

In the future, the mass application of electric aircraft will greatly improve the operating efficiency of manned and cargo vehicles, save energy and reduce transportation costs. There will also be an endless stream of novel and ingenious designs in the design of electric aircraft, as well as higher-performance axial The research and development of magnetic field motor drive systems will promote the rapid development and application of electric aircraft.